Stable oxygen-yielding washing powder



252. COMPOSITIONS,

Patented Aug. 23, 1938 UNITED STATES Examine PATENT OFFICE STABLE OXYGEN-YIELDING WASHING POWDER Karl Bauer, Frankfort-on-the-Main, and Friedrich Pressel and Hans Medweth, Rheinfelden/- Baden, Germany, assignors to Deutsche Gold und Silber Scheideanstalt vormals Roessler. Frankfort-on-the-Main, Germany, a. corporation of Germany No Drawing. Application May 25, 1935, Serial No. 23,518. In Germany June 9, 1934 2 Claims.

The object of this invention is a process for the preparation of stable oxygen-yielding washing powders, utilizing percarbonate salts such as the alkali metal percarbonates. It has been found that stable compositions are obtained when the moisture content is restricted in accordance with the following disclosure.

Washing powders are ordinarily powdery mixtures which contain besides soap powders also additional materials such as soda, water glass and the like.

Up to this time perborates, especially sodium perborate, have been used extensively in the preparation of oxygen-yielding washing powders or detergents, because these salts when mixed with soap and the other usual ingredients of washing powders, such as soda, water glass and the like, were the most stable. Perborates when mixed with soap powders, soda, water glass and the like, lose only a small per cent of their original active oxygen content after storage for one year.

The preparation of stable detergents utilizing the percarbonates has been attempted in various ways. The experiments, however, have not been entirely successful, since mixtures of the same composition as the perborate detergent mixtures are always much less stable and lose a great deal or all of their active oxygen within a comparatively short time. An effort has been made to stabilize the percarbonates by means of anticatalysts or by covering them with hydrophobic substances. However, these experiments have not given successful results.

Recently it has been found that stable mixtures of percarbonates such as sodium percarbonate with soaps and the other usual ingredients of washing powders can be produced in the absence of water. If, for example, the percarbonate is mixed with the other anhydrous ingredients oi the washing powder, mixtures are obtained which have excellent stability.

As a result of many experiments it has been ascertained that mixtures with a moisture content of about 25% are much more stable, and that mixtures with a moisture content 01' 10% or less, preferably 5-7%, have such good stability that they are in no way inferior to the detergents prepared with alkali metal perborates and remain practically unchanged after several months storage. If desired, the water can be extracted to such an extent that practically dry substances are obtained.

The novel stable oxygen-yielding washing powders containing percarbonate with which our invention is concerned may be prepared by adding an alkeiim tel-nereerbo such a sodium percarbonate, to a detergent mixture comprising soap and sodium garb onate. If desired, the detergent r'n ixtuie'may contain, in addition to the soap and soda, other substances which are usually present in washing powders such as water glass (sodium silicate). After the addition of the sodium percarbonate to the detergent mixture, the resulting mixture is dehy drated so that its moisture content falls within tl'ie'iange 5 to This range represents the per cent moisture content by weight and is based upon the weight of the ingredients comprising the complete oxygen-yielding washing powder.

To the percarbonate can be added stabilizers such as magnesium silicate, and the like.

According to the invention, in place of soap or in combination with it, soap substitutes, such as fatty alcohol sulfonates and the like, may be used.

We claim:

1. A stable alkaline oxygen-yielding washing powder which comprises an alkali metal percarbonate, sodium carbonate, and soap, the moisture content of said washing powder falling within the limits 5 to 7% by weight, based on the weight of said washing powder.

2. A stable alkaline oxygen-yielding washing powder which comprises an alkali metal percarbonate, sodium carbonate, soap, and water glass, the moisture content of said washing powder falling within the limits 5 to 7% by weight, based on the weight of said washing powder.

KARL BAUER. FRIEDRICH PRESSEL. HANS MEDWETH.

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